At one stage in the manufacturing of semiconductors and integrated circuits, a large array of the individual devices is formed on the surface of a thin circular wafer. Individual wafers typically range from two to four inches in diameter and are quite thin and fragile, requiring great care to prevent damage during handling.
During the fabrication process, these wafers are transferred from station to station in a container called a U-boat which accommodates approximately twenty-five wafers. These wafers are supported vertically in slotted edges of the U-boat and are spaced about one-fourth of an inch apart.
At one point in the process, the wafers are transferred from the U-boat to a heat-resistant quartz crystal container known as an elephant boat in which they are again supported vertically. The elephant boat with its charge of wafers is placed in a furnace at approximately 1200 degrees Centigrade for varying periods of time during the diffusion process. Following completion of the diffusion process, the wafers are returned to the U-boats for further processing including a chemical wash utilizing acids and solvents such as hydrochloric, nitric, phosphoric and hydrofloric acids, acetone, zylene, etc.
The high temperatures and the various chemical treatments render the wafers more and more fragile with each process and increasingly susceptible to contamination and corrosion in the event of exposure to body oils and acids during handling.
A common method of handling the wafers to avoid contamination and other damage is to use a specially designed tweezer with flat tips. The top and bottom surfaces of the wafer near their edges are gripped between these flat tips. This method is not altogether satisfactory because the surface area that is gripped by the flat tips may be damaged and, furthermore, not securely or stably held by the tweezer during handling. Damage and losses due to these causes reduce yield and drive up total processing costs.
An improved tool is thus needed for handling the wafers which makes it unnecessary to exert any force on the face of the wafer. This tool should firmly grip the wafer and limit the forces applied thereto to values that will not result in fracture.